Technologies for detecting or separating target molecules in a sample are used in various fields. Recently, a method of detecting or separating tumor cells from the blood has attracted much attention. For example, separating tumor cells from the blood and detecting a protein expressed from tumor cells are very important in diagnosis and treatment. Particular cells may be separated from a sample by using a magnetic separation method using a magnetic field, a three-dimensional filler method using a maximized binding surface area, a filter method using a size difference, etc. Tumor cells, however, are present in a very small amount in the blood, and according to their kinds, the kind or amount of protein expressed on their surfaces may vary. Accordingly, existing methods have limitations. Also, for use in additional assays, such as genetic variations, cytoplasm experiments, or culture experiments, which follow the separation and detection of the tumor cells, cells need to be separated intact under mild conditions. Thus, there is a need to develop a method of detecting target molecules or target cells in a sample or separating target molecules or target cells intact from a sample for use in additional assays.